/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        ListNode* newhead=new ListNode(0);
        ListNode* prev=newhead;
        ListNode* cur1=l1;
        ListNode* cur2=l2;
        int t=0;
        while(cur1||cur2||t)
        {
            if(cur1)
            {
                t+=cur1->val;
                cur1=cur1->next;
            }
            if(cur2)
            {
                t+=cur2->val;
                cur2=cur2->next;
            }
            ListNode* nowcur=new ListNode(t%10);
            t/=10;
            prev->next=nowcur;
            prev=prev->next;
        }
        prev=newhead->next;
        delete newhead;
        return prev;
    }
};
